Scientists working on the Human Genome Project are celebrating a major landmark. The international consortium has now deposited one billion base pairs of DNA sequence in public databases.

Its ultimate goal is to identify the order, or sequence, of the estimated 3 billion base pairs in the human genome.

Tuesday's celebrations mean that the project is now one third of the way to completing a working draft of the entire genome by spring next year.

Around 500 scientists at the Sanger Centre near Cambridge, UK, celebrated the event with their US colleagues, via a live video link that relayed proceedings from a special ceremony taking place at the National Academy of Sciences in Washington, DC.

Special award

To mark the achievement, the UK's Science Minister, Lord Sainsbury, has presented a special award to Dr John Sulston, director of The Sanger Centre.

But many scientists at the festivities must be wondering if they will be the first to sequence the entire human genome.

Two research groups, one publicly funded and the other working with private money, are racing to complete the first draft of the genome by next spring. At the moment there is no clear leader.

The publicly-funded Human Genome Project, which consists of research centres in the UK, US and Japan, is about to announce the first, complete sequence of a human chromosome - number 22.

Meanwhile, the Celera Corporation, a private company in Maryland, US, has already completed its first billion units of human DNA, having only begun its sequencing project in September this year.

Different routes

Celera is not making its data public. It will only disclose it to fee-paying customers.

The strategies used by the private and public sectors differ.

The Celera DNA is in short fragments, and the company needs the data obtained by publicly-funded scientists to determine how the fragments fit together. Operating 24 hours a day, Celera is sequencing a billion bases of human DNA about every three weeks.

The Human Genome Project looks at tiny sections of DNA obtained from known positions on the genome. Celera, by contrast, takes pieces from the whole genome and tries to reassemble the pieces like a jigsaw puzzle. That is why it is assisted by the public data.